1. Field of the Invention
The invention relates to a tire pressure monitoring device, more particularly to a tire pressure monitoring device including a power source and capable of wireless transmission of detected tire pressure information.
2. Description of the Related Art
Referring to FIG. 1, a conventional tire pressure monitoring device 1 is adapted to be connected to a tire valve (not shown) and includes a housing unit 11 and a tire pressure monitoring unit 12. The housing unit 11 has an upper housing part 111 that is connected to and that cooperates with a lower housing part 112 to confine an air chamber 113. The upper housing part 111 is provided with an air inlet 114 in spatial communication with the air chamber 113, and an inflating valve unit 115. A guide tube 116 connects the air inlet 114 to the tire valve. The tire can be inflated or deflated through the inflating valve unit 115. The lower housing part 112 is mounted onto the tire (not shown). The tire pressure monitoring unit 12 has a power source 121 (such as a lithium battery) mounted on the lower housing part 112, a circuit board 122 positioned between the upper and lower housing parts 111, 112 and to be connected electrically to the power source 121, and an operating module 123 mounted on the circuit board 122 and having tire pressure and temperature monitoring as well as radio frequency transmission functionalities. When the upper and lower housing parts 111, 112 are coupled together, the circuit board 122 and the power source 121 are connected electrically, and the operating module 123 begins to function so that conditions (e.g., pressure and temperature) in the tire are detected and are transmitted wirelessly to a display in a passenger room of a vehicle in order for the vehicle driver to be aware of the tire condition, thereby enhancing driving safety.
In the conventional tire pressure monitoring device 1, the upper and lower housing parts 111, 112 are coupled threadedly together to facilitate replacement of the power source 121. Replacement of the power source 121 requires disconnection of the guide tube 116 from the air inlet 114 before the upper housing part 111 can be unscrewed from the lower housing part 112, which is inconvenient to conduct. In addition, vibrations as a result of road travel can loosen the connection between the upper and lower housing parts 111, 112, thereby leading to connection failure between the circuit board 122 and the power source 121 and thereby resulting in possible air leakage from the air chamber 113. Hence, the design of the conventional tire pressure monitoring device 1 has poor reliability and instability issues.